Lifting-jack.



I No. 727,395. PATENTED MAY 5, 1903;

W. J. LOGKHART.

LIFTIN G J AGK. .APPLIOATIOI rmm 11.2. 1903.

10 MODEL.

*2 SHEETS-SHEET 1.

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No. 727,395. PATENTED MAY 5, 1903. w. J. LOGKHART. LI PTING JACK.

APPLICATION FILED MAR. 2,'1903.

I0 MODEL. 2 SHEETS-SHEET 2- llNimn STATES Patented May 5, 1903.

WILLIAM J. LOCKHART, OF BOSTON, MASSACHUSETTS.

LlFTlNG-JACK.

SPECIFICATION forming part of Letters Patent No. 727,395, dated May 5, 1903.

Application filed March 2,1903.

foaZZ whom, it may concern:

Be it known that 1, WILLIAM J. LOOKHART, of Boston, county of Suffolk, State of Massachusetts, have invented an Improvement in Lifting-Jacks, of which the following descripcan be quickly and easily operated and will havethe capability of lifting a heavy weight.

Figure 1 shows, in side elevation, a liftingjack embodying this invention. Fig. 2 is a similar View showing the handle rising preparatory to lifting the main pawl. Fig. 3 is a similar view showing the pawls in one of the positions they will occupy when the rest is being moved downward, the weight being supported by the supplemental pawl. Fig. 4 is a detail of the supplemental pawl. Fig. 5 is a cross-sectional detail of the jack, taken on the dotted line 5 5 of Fig. 1. Fig. 6 is a modified form of lifting-jack, the supplemental pawl being omitted.

The stand is herein shown as a hollow upright post a, mounted on a base a, and said stand has formed or provided on one side of it a vertical row of ratchet-teeth a 1) represents a rest which is adapted to receive a weight, it being herein shown as having a concaved seat. The rest Z) has a pair of parallel ears I) projecting from one side of it. A hand-lever c is pivotally connected to said ears of, which is adapted to operate a main pawl 01, and, as herein shown, said handlever is formed with an offset end portion 0 and a main portion. The pivot-pin 0 conmeeting the hand-lever with the ears 1), passes through the extremities of its olfset end portion. The main pawl d is pivotally connected to the hand-lever c by a pivot-pin d, which passes through said lever at the junction of its offset end portion with the main portion. The main pawl d depends from the hand-lever and its lower end engages the ratchetteeth. To the lower end of said pawl (Z a pair of arms d are loosely connected, which straddle the stand a, and a friction-roll d is journaled to the extremities of said arms. This roll and the arms supporting it hang by grav- Serial No. 145,685. (No model.)

ity, the roll resting upon the stand and sliding along on the stand as the pawl is lifted, and said parts serve as a weight by means of which the pawl is held in continuous engagement with the ratchet-teeth. As the handlever is raised the pawl will be bodily lifted, yet will remain in engagement with the ratchet-teeth, and then as said hand-lever is lowered, the pawl being in engagement with the ratchet-teeth, the rest will be raised to lift whatever weight may be placed upon it. The pivot of the pawl moves in the arc of a circle about the pivot of the hand-lever, and when the hand-lever is in its lowermost position, as shown in Fig. 1, said pivot will occupy a position at the left of a perpendicular line through the pivot of the hand-lever, and consequently the weight on the rest has a tendency to thrust the pawl inwardly and the hand-lever downwardly, to thereby securely hold said parts in such position of rest. The pawl and hand-lever having the offset end portion thus act like a toggle-jointed lever.

The parts so far described are the same in the modified form of jack shown in Fig. 6 as in Figs. 1 to 5. In Figs. 1 to 5, however, the jack is provided with a supplemental pawl e, which is adapted to support the weight while the hand-lever is being operated to again lift the main pawl, thereby producing a repeating action by which the rest may be raised step by step. The supplemental pawl e is located between the main pawl and the stand and is'adapted to engage the ratchet-teeth on the stand. The supplemental pawl c is pivotally connected at its upper end to the ears I) on the rest by the pivot-pin e, and the upper end of said pawl has an oifset portion 6 which is acted upon by a spring e which holds said pawl in engagement with the ratchet-teeth. The supplemental pawl is provided near its lower end with a pair of ears c which project one at each side of the row of ratchetteeth, said ears serving to guide the lower end of the pawl, and the lower end of the supplemental pawl has also a laterally-projecting finger-piece 6 which may be engaged by the operation whenever desired to positively disengage the pawl from the ratchet-teeth. The supplemental pawl is adapted to be engaged by the main pawl when the hand-lever is in its lowermost position, as shown in Fig.

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l, and by such engagement will be crowded more firmly into engagement with the ratchetteeth. When the hand-lever is moved into its lowermost position, the supplemental pawl may and preferably will be slightly lifted and held above the ratchet-teeth, as shown in Fig. 1, so that the weight will be supported entirely by the main pawl. Whenever it is desired to lower the rest of the jack, (shown in Figs. 1 to 5,) the hand-lever will be raised gradually to enable the supplemental pawl to be disengaged from the ratchet-teeth and being manipulated by the finger-piece will be lowered one or more teeth and again brought into engagement with said ratchet-teeth, and while the hand-lever is raised the main pawl will be lifted by it free from the ratchet-teeth, and at such time the Weight will be supported by the supplemental pawl. The main pawl is then disengaged from the ratchetteeth, lifting the friction-roll, and is lowered by lowering the hand-lever.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a lifting-jack, the combination of a.

hollow upright stand having a vertical row of ratchet-teeth formed on its outer side, a rest adapted to receive the weight, a post sliding in said hollow stand on which said rest is mounted, ears on one side of said rest, a handlever having an offset end portion, a pivot-pin passing through the extremity of said offset end portion and through the ears on the rest, a pawl pivotally connected to the hand-lever at the junction of its offset end portion with its main portion, and means for holding said pawl in engagement with the ratchet-teeth, substantially as described.

2. In a lifting-jack, the combination of a hollow upright stand having a vertical row of ratchet-teeth formed on its outer side, a rest adapted to receive a weight, a post sliding in said hollow stand on which said rest is mounted, ears on one side of said rest, a handlever having an offset end portion, a pivot-pin passing through the extremity of said offset end portion and through the ears on the rest, a pair of arms loosely connected to the lower end of said pawl which straddle the stand and a friction-roll journaled to the extremities of said arms, substantially as described.

3. In a lifting-jack, the combination of a hollow upright stand having a vertical row of ratchetteeth, a rest adapted to receive a weight, a post sliding in said hollow stand on which said rest is mounted, ears on said rest, a hand-lever pivotally connected to said ears, a main pawl pivotally connected to said hand lever below its pivotal connection with the ears, and a supplemental pawl also pivotally connected to said ears between the main pawl and the stand, substantially as described.

4. In a lifting-jack, the combination of a hollow upright stand having a vertical row of verses lever below its pivotal connection with the ears, and a supplemental pawl also pivotally connected to said ears between the main pawl and the stand, having a lateraly-projecting finger-piece, substantially as described.

5. In a lifting-jack, the combination of a hollow upright stand having a vertical row of ratchetteeth, a rest adapted to receive a weight, a post sliding in said hollow stand, on which said rest is mounted, ears on said rest, a hand-lever pivotally connected to said cars, a main pawlpivotally connected to said handlever below its pivotal connection with the ears, and a supplemental pawl also pivotally connected to said ears between the main pawl and the stand, adapted to be engaged and moved toward the ratchet-teeth, by said main pawl, substantially as described.

6. In a lifting-jack, the combination of a hollow upright stand having a vertical row of ratchet teeth, a rest adapted to receive a weight, a post sliding in said hollow stand on which said rest is mounted, ears on said rest, a hand-lever having-an oifset end portion, a pivot-pin passing through the extremity of said offset portion, and through the ears on the rest, a pawl pivotally connected to the hand-lever at the junction of its offset end portion and its main portion, a supplemental pawl located between the main pawl and stand which is pivotally connected to said ears, and is adapted to be engaged and moved toward the ratchet-teeth by said main pawl, substantially as described.

7. In a lifting-jack, the combination of a hollow upright stand having a vertical row of ratchetteeth, a rest adapted to receive a weight, a post sliding in said hollow stand on which said rest is mounted, ears on said rest, a hand-lever having an offset end portion, a pivot-pin passing through the extremity of said offset end portion and through the ears on the rest, a pawl pivotally connected to the hand-lever at the junction of its offset end portion and main portion, a pair of arms loosely connected to the lower end of said main pawl which straddle the post, a frictionroll journaled to the extremities of said arms, a supplemental pawl located between the main pawl and stand which is pivotally connected to said ears, and is adapted to be engaged by said main pawl, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM J. LOOKHART.

Witnesses:

B. J. Novas, H. B. DAVIS. 

